Production of solvents



May 25, 1943- J. E. HARVEY, .JR 2,319,991

PRODUCTION F soLvENTs Filed Aug. 14, 1940 .fre/Pp/NG cfm/1455 E ali-nii?? fafa/aaf- Patented May 25, 1943 PRODUCTION OF SOLVENTS Jacquelin E. Harvey, Jr., Atlanta, Ga., assignor of one-half to Southern Wood Preserving Company, East Point, Ga., a corporation of Georgia Application August 14, 1940, Serial No. 352,672

1 Claim.

The present invention relates to the production of Valuable liquids from tars of aromatic content and fractions thereof, crude and/or refined.`

An object of the present invention is the subjection of tars of aromatic content and fractions thereof, crude and/or rened, to the action of hydrogen in step-wise manner, whereby to provide solvents of increased solvency, said solvents being characterized, when compared to the immediate starting material, by a fractional increment in the low boiling range in excess of fractional increment in the higher boiling range.

l A further object of the present invention is the production of rened solvents of lowered corrosivity and'superior solvency, the characteristics of which are, among other things, dependent upon hydrogen supply as hereafter explained.

Starting materials of the present process include tars and fractions thereof of aromatic content characterized by content of oxygenated compounds and sulphur, said tars being derived from coal, petroleum, and gas or gases containing carbon; as for instance coke oven tar, water gas tar,l gas house tar and tars of aromatic content in general; tars produced by cracking hydrocarbons; tars resulting from the action of hydrogen on hydrocarbons; high boiling extractions of carbonaceous substances; high boiling hydrocarbons of aromatic content having oleflnic and/or naphthenic content.

Starting materials of the present process also include tars of aromatic content from which 10W boiling fractions have been removed, as for instance tars from which solvent oils have been removed. Viewed broadly, the starting materials of the present process are tars of aromatic content, fractions of said tar more viscous than the starting material due to removal of low boiling fractions from the starting material, high boiling fractions and pitches. Materials previously subjected to the action of hydrogen are suitable starting materials.

Especially attractive as starting materials are the tars from high temperature coke ovens which are available in large quantities at low prices.

The present invention may be viewed broadly as a process for the production of refined solvents of lowered corrosivity by subjecting the starting material in step-wise manner to the controlled action of hydrogen whereby to produce said solvent having enhanced solvency, and as compared tothe immediate parent material, an increment of fractions in the lower boiling range in excess of fractional increment in the higher boiling range.

The invention will be understood from the following description of illustrative steps comprising various methods of securing the objects of the invention, when read in connection with the accompanying drawing wherein the figure is a ditol agrarnmatic sketch of an apparatus for carrying out a form of the process of the invention and wherein the nature of the step carried out in each chamber and the contents thereof are indicated by legend.

Example 1.-A sulphur bearing coal tar creosote, characterized by content of oxygenated compounds, a coke residue in excess of 1%, a specific gravity of in the order of 1.06, and substantially 25% residue above 355 C., is subjected to the action of hydrogen at 395 C. and 200 atmospheres pressure whereby to lower sulphur content thereby lowering corrosivity, at least providing for lowered corrosivity in the finished material as hereinafter explained. The material of lowered sulphur content is then passed in liquid phase to a high pressure reaction vessel while simultaneously flowing hydrogen therewith in the presence of molybdenum oxide catalyst and a material adapted to influence the decomposition of oxygenated compounds contained in the starting material, at a temperature of 400 C. and 300 atmospheres pressure. The time of contact is one hour and the flow of gas 15,000 cubic feet per barrel refined creosote. The beneiiciated creosote upon inspection will be found to have a lowered coke residue, boiling range, specific gravity, viscosity and oxygen content. Solvency in some of the lower fractions will be lowered as compared to solvents extantof comparable boilingl range.

The beneciated creosote is stripped to an upper limit of 300 C. and at least a portion of the low boiling fractions thereof is passed through a high pressure reactor at 455 C. and 200 atmospheres pressure while contacting a molybdenum oxide catalyst. The flow of hydrogen is so controlled as tofinduce a solvent having increased solvency and an increment of fractions in the lower boiling range in excess of fractional increment in the higher boiling range.

The solvent so produced may be fractionated to provide a refined solvent of lowered corrosivity of any boiling range within the limits of the immediate parent material, as for instance:`

' The refined solvents vmay serve as substitutes for the material having the boiling range or ranges of the commercial solvents noted above.

In the foregoing example it will be noted that the present process provides Ya method for contacting the starting material with hydrogen whereby to lower sulphur content, thereafter, contacting the material of lowered sulphur content with hydrogen whereby to produce an intermediate product ofelowered solvency, specific gravity, boiling range, coke residue, and viscosity; stripping from the beneciated material a low boiling fraction thereof and subjecting at least a portion of said low ends to the controlled action of hydrogen whereby to enhance solvency and produce, as compared to the immediate starting material, an increment of fractions in the lower boiling range in excess of fractional increment in the higher boiling range, thus providing the reiined solvent of lowered corrosivity of the present process.

Looked at in one manner the present process provides a method for treating tars cf aromatic content, and fractions thereof, with hydrogen in step-wise manner whereby to provide refined solvents of lowered corrosivity, said solvents being characterized by increased solvency as compared to their immediate starting material as heretofore disclosed. The step-wise action of hydrogen being further characterized by providing hydrogen in flow that depolymerizes ring multiplicities thereby inducing lowered specific gravity, coke residue, boiling range, solvency and viscosity, and last, by providing hydrogen in flow that, among other things, increases solvency.

The step-wise action of hydrogen thus provides a method for securing refined solvents of lowered corrosivity and superior solvency from high boiling hydrocarbons of aromatic content, said high boilers characterized by the presence of ring multiplicities of great thermal susceptibility.

Example V2,-A sulphur containing coal tar, specific gravity 1.1641, a coke residue in excess of 1%, and in excess of 35% boiling at 355 C., and further characterized by content of oxygenated compounds is subjected to the action of hydrogen at 380 C. and 300 atmospheres pressure for such a length of time as to lower sulphur content. The coal 'tar of lowered sulphur 'content is then passed in liquid phase through a high pressure reaction vessel while simultaneously flowing hydrogen therewith at a pressure of 300 atmospheres and a temperature of 410 C.; time of contact one hour, catalyst vanadium oxide and a material selected from the group consisting of halogens, 'halids, and derivatives thereof including substitution and addition products thereof, and i'low of hydrogen 15,000 cubic feet per barrel feed stock. The thus treated coal tar is found to have a lowered specic gravity, viscosity, coke residue, boiling range, and oxygen content. In some of the fractional parts of the treated coal tar there will be lowered solvency as compared to solvents extant of comparable boiling range.

The beneficiated tar is then stripped to an upper limit of 360 C. and the low ends thereof subjected to the action of a flow of hydrogen at 450 C. and 200 atmospheres pressure and for such a length of time as to increase solvency and produce an increment of fractions in the lower boiling range in excess of fractional increment in the higher boiling range, thus providing the refined solvent of the present process.

Example 3.-A high boiling fraction of coal tarcharacterized by sulphur content, and having.

initial boiling point of substantially 245 C. is subjected to the action of hydrogen atY 375 C. and 250 atmospheres pressure for such a length of tiineas to reduce sulphur content. The material of reduced sulphur content is then passed in liquid phase through a high pressure reaction chamber while simultaneously flowing hydrogen therewith at a temperature of 410 C. and 300 atmospheres pressure; the catalyst is molybdenum oxide and tin chloride and the flow of hydrogen so controlled as to induce no substantial percentage of coke or carbon in the reaction chamber, nor to induce any substantial percentage of chain structures that would preclude the provision of the solvent of enhanced solvency of the present process.

Upon inspection the beneiiciated coal tar fraction will be found to have a lowered specific gravity, coke residue, boiling range, viscosity and oxygen content, and, in the case of some fractional parts of the beneciated material, a lowered solvency as compared to solvents extant.

The benelciated material is stripped to 375 C. and the low boiling fractions thereof subjected to the action of hydrogen at 450 C. and 200 atmospheres pressure; flow of hydrogen 5,000 cubic feet per barrel feed and the time so controlled as to provide an increment of low boiling fractions in excess of fractional increment in the high boiling range. The solvency of the finally processed material is in excess of the immediate starting material. The time of the last step may be a fractional minute, or more, as for instance several minutes.

The residue incidental to the stripping step may be recycled or used as an article of commerce of enhanced value, as for instance binders or the like.

The starting material of high carbon content, as for instance coke oven tar or fractions thereof is characterized by, in their raw state, such a percentage of high molecular complexes or polymerized products that the refined solvents of the present invention are not possible of manufacture therefrom directly, but must be produced in step-wise manner, as heretofore explained, whereby, among other things, the action of hydrogen depolymerizes said molecular complexes contained in the starting material.

The depolymerized or partially depolymerized tar or fraction thereof is then stripped of a percentage of its low ends whereby to provide the intermediate parent material of the refined solvents of lowered corrosivity, said refined solvents characterized, as compared to the immediate starting material, by an increment of fractions in the lower boiling range in excess of fractional increment yinthe higher boiling range. The residue incidental to said stripping may, because of its depolyrnerized or partially depolymerized condition serves as recycled material to the end that conversion of the starting material in the percentage finally remaining liquid approaches volumefor volume of the starting material into the refinedA solvents of the present invention.

In the conversion of starting materials, partially or approaching unity, into the reiined solvents of lowered corrosivity, temperatures as low as 300 C. may be employed; pressures as low as 50 atmospheres may be used. However, temperatures and pressures of an increased range provide better lcommercial practice. The time element is desirably that period which affords commercial recoveries of the product of, and incidental to, thepresent process. Temperatures are preferred that cause no substantial amount of coking.

G-as flows are usually held in excess of 2,000 cubic feet per barrel feed treated. In the stepwise application of hydrogen a few trials when using any of the starting materials will determine the gas iiow when coordinated with the selected temperature and pressure conditions which effect said depolymerization. The gas flow in this instance may bel a variable quantity because of the varying ranges of coordinated temperature and pressure that may be selected. When using a chosen coordination of temperature and pressure, a few trials will readily determine the gas iiow that provides depolymerizing conditions to the end that solvency, specific gravity, viscosity, and boiling range are lowered. v i

Concerning the gas fiow that increases solvency and provides an increment of low boiling fractions in excess of fractional increment in the high boilingrange, said gas flow is held at that point which induces no percentage of finally liquid chain structures that will preclude the enhanced solvency of the present invention. For a given coordination of temperature and pressure, the gas flow in the last instance is lower than the gas iiow in the preceding instance.

Using some starting materials a gas flow of l0,000-l5,000 cubic feet per barrel feed, or higher, has proven satisfactory for depolymerizing conditions, and,.a gas i-low of in the order of 6,000- 8,000 cubic feet per barrel feed has proven satisfactory for solvency induction, however, lower gas flows may be used.

Viewed broadly, the gas flow in the instance of depolymerizing conditions may be lower than 10,000 cubic feet per barrel feed, and the ow in the last instance is held at that point that increases solvency.

In the hydrogen action that reduces sulphur content, the action of hydrogen may be effected in an autoclave or in a continuous plant, and in the event of continuous practice, the gas flow is maintained so as to assist in sulphur reduction and the removal thereof from the'reaction zone, the while inducing no substantial percentage of carbon or the like, nor percentages of liquid chain structures that would preclude the provision of the refined solvents of superior solvency of the present process.

By the term beneciated as used herein and 1n the appended claim is meant the starting material at least once subjected to the action of hydrogen in accordance with the present process.

After1 the starting material has been subjected to depolymerizing action, the stripping step may be effected at any point selected within a wide range to provide a cut capable of providing, after further processing, substitutes for the boiling range or ranges or benzol, toluol, xylol, the various naphthas, and the various plasticizers.

Thus, the depolymerized starting material may be cut according to the need at hand, said out then being subjected to the action of hydrogen that increases solvency as heretofore explained.

In the step that effects depolymerization of the high molecular complexes contained in the starting material, the inclusion of a catalyst adapted to inuence the decomposition of oxygenated compounds contained therein, enhances said depolymerization and allows the reduction of specie gravity, viscosity, and coke residue to process at an enhanced rate.

The catalysts of the present process are oxides and a material adapted to inuence aforesaid decomposition of oxygenated compounds, said material being selected from the group consisting of halogens, halids and derivatives thereof including substitution and addition products thereof. Catalysts may be employed in any effective form as for instance asV pellets, comminuted, or supported on carriers.

If desired, comminuted catalyst may be used in the hydrogen step characterized by depoly merization, and in the step characterized by solvency increase, a rigid catalyst may be used.

By the term multiplicity of rings, high molecular complexes and polymerized products are meant high boiling fractions of aromatic content a portion of which at least may be viewed as ring multiples; or, in said terms, any or all, may be used to describe high boiling fractions of the starting material 4especially susceptible to thermal degradation.

When subjecting high boiling fractions of the starting materials to the process of the present invention, it may be desirable prior to the depolymerizing step, or the sulphur reduction step, to at least partially depolymerize the molecular complexes by use of a solvent. Said solvent may be added in a small amount, or up to volume for volume or more. Refractory solvents may be desirable, but others more susceptible to the reaction conditions inherent in and to the present process are usable.

Concerning solvents, it `may be said that tar itself, as for instance, high temperature coke oven tar is constituted of high molecular complexes dissolved, cut back, or depolymerized with a solvent, said solvent being the lower boiling fractions of said tar.

The action of hydrogen may be effected in one or more cycles or chambers, with or without releasing the pressure and with or without variation of process controls.

Various modes of practicing the present invention are possible, as for instance the depolymerized starting material may be stripped by gas movement; the 10W ends thus stripped may then, with or without releasing pressure, be subjected to further action of hydrogen. Or, the desired stripped material may be obtained by partial release of pressure which would correspond to the fractional recovery desired or predetermined.

As an example of the halogens, halids and derivatives thereof that may be employed for inuencing the decomposition of oxygenated cornpounds may be mentioned iodine, chlorine and bromine; metallic chlorides except the chlorides of sodium and cal'cium; organic chlorides, as for instance ammonium chloride; hydriodic acid is especially effective, as is iodoform.

The process may be practiced in an autoclave and/or a single reaction chamber, a series thereof, a parallelism thereof, including a multiplicity thereof.

The refined solvent of the present invention may be fractionated to provide solvents and/or plasticizers of Various boiling ranges, and in the instance where solvents are processed from a deep cut on the depolymerized material, the highest boiling fractions thereof or others may serve as a substitute for certain plasticizers.

In the first cycle of hydrogen action that reduces sulphur content, said reduction of sulphur may be accomplished in the presence of a catalyst. Catalysts effective in the presence of hydrogen are usable, as for instance the oxides and/or suldes of molybdenum, vanadium, uranium, cobalt, tin, manganese, tungsten, or the like.

In the disclosure herein made the removing of low boiling fractions by gas movement or pressure release is considered the equivalent of distillation.

The term pitch as used herein includes the higher boiling fractions of tar, in other words, tar from which low boiling ends have been stripped, such low boiling ends being suitable for use per se as creosote, other wood preservative or solvent. For instance, the final residue resulting from evaporating tar to dryness or substantial dryness (coke or hard pitch) and then stripping wood preservative from the distillate is a very suitable pitch for use as a starting material of the present process.

When reference is made t0 high molecular complexes contained in the starting material, and when the starting material contains low boiling fractions that are not considered high molecular complexes, it is of course obvious that the high molecular complexes contained in the starting material are to a certain extent depolymerized by the solvent present.

It will be seen that by reduction of sulphur content of the material under treatment during any stage of hydrogen action, the oxide catalyst used during subsequent stages is at least partially protected from the effect ofthe sulphur.

Minor changes may be made Within the scope of the appended claim without departing from the spirit of the invention.

I claim:

In the production of solvents from a mixture of sulfur-bearing and oxygen-lcontaning high temperature coal tar fractions, the process which comprises: subjecting said ltar fractions to the action of hydrogen with time, temperature and pressure so controlled as to reduce sulfur content; subjecting said tar fractions of lowered sulfur content to the action of a relatively high flow of hydrogen Whilst contacting as catalytic materials an oxide of a metal and a material selected from the group consisting of halogens, halids and derivatives thereof including addition and substitution products thereof, said hydrogen flow being selected from the range above 10,000 cubic feet per barrel material treated, at a pressure and temperature of at least 300 atmospheres and 400 C., respectively; carrying on the process for such a length of time as to provide a material of lowered specic gravity and Viscosity; stripping low boiling fractions from the beneciated material;

and providing in the stripped low boiling mate-V rial an increment of fractions in the lower boiling range in excess of fractional increment in the higher boiling range by subjecting said stripped low boiling material to the action of a relatively low liow of hydrogen, a temperature and pressure of Iat least 300 C. and 50 atmospheres, respectively, to produce a solvent.

J ACQUELIN E. HARVEY, JR. 

